Cal Mag in tap water

[SeedlessOne]

Ok so is there any reason to put cal mag in tap water. i was going to use RO water so i bought some cal mag. There is no where to buy any RO water in a reasonable distance. So i am going to start using tap water that i let sit out for 48 hours. So my question is should i still use the cal mag even though i am using cal mag? Also should i use 1 tps or 2 tps per gallon if i using fox farm grow big. As ive seen two different feeding charts...thanks guys

[BlueBear]

You can go with the feeding chart on the bottle, just start off at half strength for the first 2 feedings. Yes it is good to use with any kind of water. It will bring alot of secondary menerals that help the plant produce in needed areas. Also, you should be good with leaving your water out for only 24 hours.
Adieu

[stinkyattic]

Unneccessary; tap water has Ca and Mg in it usually anyway.
But you will want to add silica.

[invision]

i use calmag plus with tapwater and distilled water just depends if um lazy to go to the store the last few weeks ive used tap water to raise my PH with the calmag plus and she is fine just use 1tbs per gallon you can use this right up until you flush her before harvest